Roller derby is a contact sport played by two teams, each team roller skating in the same direction around a track. Generally, game play consists of a series of short matchups, or “jams,” in which both teams designate a scoring player, or “jammer,” who scores points by lapping members of the opposing team. Remaining team members attempt to assist their own jammer while hindering the opposing jammer.
Players typically skate on four-wheeled “quad” roller skates. Quality skates can cost up to $1000.00 per pair. A set of eight wheels begins at approximately $30.00 for non-competitive materials and construction and extends to approximately $150.00 for top-end competitive quality.
A player often desires to change one or more wheels during the course of a roller derby game. For example, a single wheel may become worn or damaged from expected wear and tear and require replacement. Alternatively, changing play style or track conditions such as accumulating dirt, debris, and/or moisture may necessitate a full transition of all eight wheels from a first wheel type to a second wheel type more appropriate for the new conditions (e.g., different wheel width, durometer hardness rating, or tread).
Furthermore, initial assumptions about the track may necessitate a wheel change. That is, in the early days of the sport, roller derby games were played on specialized, banked tracks. These tracks were consistent in size, shape, and material and were specially designed for roller derby skates. As time passed, the size of the sport outgrew the number of specialized tracks, and roller derby tracks began to appear on other sporting surfaces such as wooden or rubber basketball courts, running tracks, and more. Due to varying track conditions, players employ different wheels at different tracks. Depending on whether initial assumptions about the track in use are correct (e.g., hardness of the track, friction offered by the track surface), a player may need to change wheels after the start of play to adjust as appropriate.
A traditional wheel changeover for a full set of eight wheels currently takes between twenty and thirty minutes and requires special tooling, e.g., a bearing press. The changeover is also difficult to accomplish with the skates on the player's feet. As a result, wheel changes—whether for one wheel or a whole set of eight—require the player to exit the game, remove one or both skates depending on the number of wheels to be changed, and remain sidelined for a lengthy period of time. Because wheel changes are so inconvenient, players in need of a wheel change often forego the long removal from play, electing to play with a damaged wheel or a set of wheels inappropriate for current playing conditions.